perf/core: Save the dynamic parts of sample data size

The perf sample data can be divided into parts.  The event->header_size
and event->id_header_size keep the static part of the sample data which
is determined by the sample_type flags.

But other parts like CALLCHAIN and BRANCH_STACK are changing dynamically
so it needs to see the actual data.  In preparation of handling repeated
calls for perf_prepare_sample(), it can save the dynamic size to the
perf sample data to avoid the duplicate work.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Tested-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Song Liu <song@kernel.org>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20230118060559.615653-2-namhyung@kernel.org

diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 03949d0..16b9800 100644 (file)
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -1103,6 +1103,7 @@ struct perf_sample_data {
         */
        u64                             sample_flags;
        u64                             period;
+       u64                             dyn_size;
 
        /*
         * Fields commonly set by __perf_event_header__init_id(),
@@ -1158,6 +1159,7 @@ static inline void perf_sample_data_init(struct perf_sample_data *data,
        /* remaining struct members initialized in perf_prepare_sample() */
        data->sample_flags = PERF_SAMPLE_PERIOD;
        data->period = period;
+       data->dyn_size = 0;
 
        if (addr) {
                data->addr = addr;

diff --git a/kernel/events/core.c b/kernel/events/core.c
index d56328e..827082d 100644 (file)
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -7586,7 +7586,7 @@ void perf_prepare_sample(struct perf_event_header *header,
 
                size += data->callchain->nr;
 
-               header->size += size * sizeof(u64);
+               data->dyn_size += size * sizeof(u64);
        }
 
        if (sample_type & PERF_SAMPLE_RAW) {
@@ -7612,7 +7612,7 @@ void perf_prepare_sample(struct perf_event_header *header,
                        data->raw = NULL;
                }
 
-               header->size += size;
+               data->dyn_size += size;
        }
 
        if (sample_type & PERF_SAMPLE_BRANCH_STACK) {
@@ -7624,7 +7624,7 @@ void perf_prepare_sample(struct perf_event_header *header,
                        size += data->br_stack->nr
                              * sizeof(struct perf_branch_entry);
                }
-               header->size += size;
+               data->dyn_size += size;
        }
 
        if (sample_type & (PERF_SAMPLE_REGS_USER | PERF_SAMPLE_STACK_USER))
@@ -7639,7 +7639,7 @@ void perf_prepare_sample(struct perf_event_header *header,
                        size += hweight64(mask) * sizeof(u64);
                }
 
-               header->size += size;
+               data->dyn_size += size;
        }
 
        if (sample_type & PERF_SAMPLE_STACK_USER) {
@@ -7664,7 +7664,7 @@ void perf_prepare_sample(struct perf_event_header *header,
                        size += sizeof(u64) + stack_size;
 
                data->stack_user_size = stack_size;
-               header->size += size;
+               data->dyn_size += size;
        }
 
        if (filtered_sample_type & PERF_SAMPLE_WEIGHT_TYPE)
@@ -7693,7 +7693,7 @@ void perf_prepare_sample(struct perf_event_header *header,
                        size += hweight64(mask) * sizeof(u64);
                }
 
-               header->size += size;
+               data->dyn_size += size;
        }
 
        if (sample_type & PERF_SAMPLE_PHYS_ADDR &&
@@ -7738,8 +7738,11 @@ void perf_prepare_sample(struct perf_event_header *header,
                size = perf_prepare_sample_aux(event, data, size);
 
                WARN_ON_ONCE(size + header->size > U16_MAX);
-               header->size += size;
+               data->dyn_size += size + sizeof(u64); /* size above */
        }
+
+       header->size += data->dyn_size;
+
        /*
         * If you're adding more sample types here, you likely need to do
         * something about the overflowing header::size, like repurpose the